The decision shutters a decades-old state-run news agency widely viewed as offering professional and semi-independent coverage, while putting a reconstituted news service in the hands of a Kremlin loyalist. Since returning for a third time as president last year, Mr. Putin has taken several steps that critics have denounced as a strangulation of political rights and open debate, concentrating power in an ever tighter circle of allies.

The decree comes at a time when Russia has become increasingly assertive on the world stage, most recently in the tug of war with the European Union over political and economic relations with Ukraine, a country with deep historical and cultural links that Mr. Putin and others here believe bind it to Russia, not the West.

The Kremlin’s intense lobbying and strong-arming of Ukraine’s embattled president, Viktor F. Yanukovich, have been a principal grievance of the hundreds of thousands who have poured into the streets in the last two weeks. The reorganization of Russia’s state news media occurred only days after a meeting between the two leaders — and unconfirmed rumors that they had reached a secret deal to forge a strategic partnership — served to intensify the protests.

Mr. Putin’s presidential chief of staff, Sergei B. Ivanov, said the decision to close the news service was part of an effort to reduce costs and make the state news media more efficient. But RIA Novosti’s report on its own demise said the changes “appear to point toward a tightening of state control in the already heavily regulated media sector.” Its executive editor, Svetlana Mironyuk, the first woman to lead the agency, appeared before her stunned colleagues and apologized for failing to preserve what she called the best news organization ever built by state money, according to a video recording of the meeting.

The two agencies will be absorbed into a new state media organization known as Rossiya Sevodnya, or Russia Today. In a separate decree, Mr. Putin appointed Dmitry K. Kiselyov as executive director of the organization. Mr. Kiselyov, a television executive and host, is an avowed pro-Kremlin figure who has provoked controversy with starkly homophobic remarks and virulent commentary suggesting foreign conspiracies are threatening Russia.

The decrees caught the agencies’ employees, its executives and even some government officials by surprise. Mr. Putin made the changes without prior notice or public debate, as is often the case here. His decree said that the new agency would focus on providing news about Russia to an international audience; the agency’s directors will be directly appointed by the president’s office.

The reasons behind the timing were unclear and, to many, puzzling. RIA Novosti is one of the official sponsors of the Winter Olympics to be held in the Russian resort of Sochi in February, and its employees have been deeply involved in organizing preparations for news coverage there. There have been some calls for boycotting the Games, citing Russian policies, including a new law prohibiting advocacy of nontraditional sexual relationships, that have prompted harsh criticism from rights organizations.

“Russia has its own independent politics and strongly defends its national interests,” Mr. Ivanov, a close ally of Mr. Putin’s, said in remarks to reporters, according to RIA Novosti. “It’s difficult to explain this to the world, but we can do this and we must do this.”

He suggested that Russia had had some difficulties in successfully explaining its views abroad. “We must tell the truth, make it accessible to the most people possible, and use modern language and the best available technologies in doing so,” he added.

RIA Novosti’s roots extend to World War II, when it was founded as the Soviet Information Bureau two days after the Nazi invasion of the Soviet Union. According to the agency, it has correspondents in 45 countries and provides reports in Russian and 13 other languages.

It was renamed after the collapse of the Soviet Union in 1991, and while it continued to serve as an official news agency, its reporting earned greater respect for its balance and diversity of viewpoints.

That troubled at least some here. Maxim L. Shevchenko, a prominent television personality, called the reorganization “a sensible step” in a post on Twitter. “The nest of anti-Russian media forces has been destroyed,” he wrote.

That an official news agency could be considered hostile to its own government reflected some deep divisions within Russia’s political elite. The new agency’s name, Rossiya Sevodnya, is the original name of the Kremlin’s international television network, now re-branded simply as RT and known for its jaundiced view of the United States and other Western countries. The decree, which takes effect immediately, did not link the two organizations.

Aleksei A. Navalny, the anticorruption blogger and opposition leader, lamented the demise of a “strong Soviet brand” in his own posting on Twitter and said Russia Today, as a brand, was “something repulsive.”

Andrei Miroshnichenko, an independent media critic here, said RIA Novosti and the other state news agency, Itar-Tass, had in effect competed for resources and influence.

He said RIA Novosti had become the most respected news agency in the former Soviet Union, one he associated closely with the presidency of Dmitri A. Medvedev, who has served as prime minister since Mr. Putin returned to the presidency last year. In that way, dismantling the news service is another step by Mr. Putin to erase any legacy of Mr. Medvedev’s presidency, and his “modernization initiative.”

The new agency, Mr. Miroshnichenko said, would now revert to its mission before the dawn of “the post-Soviet era” as an arm of “foreign propaganda,” while Itar-Tass would focus on domestic news.

The most pointed criticism of Mr. Putin’s decrees focused on the choice of Mr. Kiselyov as the new agency’s director. He is known for sharp commentaries in defense of Mr. Putin’s Russia that often reflect his belief that there are foreign conspiracies aimed at weakening the nation. He has described the current protests in Ukraine as a provocation by a coalition of Sweden, Poland and Lithuania like the one that Peter the Great defeated in 1709 in the Battle of Poltava in what is modern Ukraine.

“This week the coalition has shown its full strength,” Mr. Kiselyov said on his weekly talk show, “Vesti Nedeli,” or “News of the Week,” on the state television network, Rossiya. “It looked like a thirst for revenge for Poltava.”

Remarks he made last year resurfaced during the recent debate over the new prohibitions on “propaganda” of nontraditional sexual relationships. “I think it is too little to fine gays for homosexual propaganda,” he said. “They should be forbidden from donating blood, sperm. And in the case of an automobile accident, their hearts should be buried in the ground or burned.”

There were calls for a criminal inquiry for his remarks, but none were undertaken. Mr. Kiselyov denied that he or the remarks he made were homophobic.

His views on journalism, he acknowledged in a recent interview with the online news organization Lenta.ru, had evolved significantly, particularly after he worked in Ukraine during the previous political protests there that became known as the Orange Revolution.

“I understood that objective journalism, distilled, is absolutely not in demand,” he said in the interview. “The basic difference between post-Soviet and Western journalism is that for us it is necessary to create values and not to renew them, to produce values and not to reproduce them, as is basically done in the West.”